The discussion centers on the presence of belly buttons in mammals, specifically questioning why they are not easily visible in animals like cats and guinea pigs. It is noted that all placental mammals, including dolphins, have an umbilical cord during fetal development, which typically leaves a small, flat scar that is often concealed by fur. Unlike humans, who have a distinct belly button scar, these animals do not exhibit the same prominent feature. The conversation also touches on the mechanics of umbilical cord detachment, explaining that in most cases, the cord tears off naturally during birth, particularly in animals that give birth standing up. Instances are shared where kittens had cords that remained attached for several days, complicating their separation.